The present invention relates in general to window-mounted Venetian blind assemblies, and more particularly to a Venetian blind assembly for use with a window in a moving vehicle, such as a recreational camper or van, or for use with a window inclined from a vertical plane, such as a skylight.
A typical Venetian blind assembly of the type under consideration includes a top rail member fixed in position above an associated window, a collapsible ladder and slat structure suspended from the top rail member, and a movable bottom rail member connected to the lower end of the ladder and slat structure. The bottom rail member can be moved upwardly toward the top rail member by use of two or more lift cords to progressively collapse the ladder and slat structure so as to raise the blind, or the lift cords can be released to allow the bottom rail member to move downwardly by gravity so as to lower the blind.
The ladder and slat structure includes a plurality of horizontally extending parallel slats resting on the crosspieces of two or more vertically extending flexible tapes or ladders, each having a pair of sidepieces, the upper ends of which are connected to the top rail member, the lower ends of the ladder sidepieces being connected to the bottom rail member. A user actuated tilting mechanism located within the top rail member causes the sidepieces of each ladder to simultaneously move in opposite vertical directions wherein the slats can be titled to open or close the blind by a predetermined amount as is well known in the art.
In adapting the above-noted Venetian blind assembly for use in a moving vehicle, or for use with an inclined window, such as a skylight, it becomes necessary, when the blind is in a lowered condition, to releasably lock and hold the bottom rail member in position below the associated window so that it will not swing out away from the associated window.
Even with the bottom rail member fixed in position relative to the top rail member, means should be provided to maintain and stabilize the position of the ladder and slat structure extending between the rail members. If such stabilizing means is not provided, the ladder and slat structure will repeatedly bang against the associated window of a moving vehicle, or it will sag in an unsightly manner when being used with a window inclined from a vertical plane, such as a skylight.
To the present inventor's knowledge, the usual means for providing the required stabilization of the ladder and slat structure as set forth above is to pull down on the bottom rail member when the blind is fully lowered so as to place tension on the ladders, and then lock or fix the bottom rail member in position so as to maintain the tension force on the ladders. Thus, the tensioned ladders limit the movement of the slats thereby stabilizing the ladder and slat structure.
Numerous disadvantages result from the abovenoted stabilization technique. For example, the material forming the ladder can, over a period of time, be stretched, thus requiring that the fixed position of the bottom rail member relative to the top rail member be changed to increase the distance between the rail members to ensure desired tensioning of the ladders. Also, tensioning of the ladders interferes with the smooth operation of the slat tilting mechanism due to frictional binding between the tensioned ladder sidepieces and the slats. Also, the tension forces can cause unsightly arcing or bowing of the bottom rail which is typically not designed to resist forces on it tending to cause such arcing or bowing. Also, it can be seen that the length of the blind must be accurately controlled when it is to be installed on a window frame providing, at a fixed vertical distance apart, the retaining means for fixing in position both of the rail members, i.e. the length of the blind must be slightly shorter than the distance between the top rail member retaining means and the bottom rail member retaining means so as to provide vertical tensioning of the blind when locked in position.
Accordingly, it is a primary purpose of the present invention to provide a Venetian blind assembly which overcomes each of the aforementioned shortcomings without offsetting disadvantages.